[clang] [clang-tools-extra] [clang] CodeComplete fix for addr of deduced-this methods (PR #152445)

[Mythreya Kuricheti via cfe-commits]

https://github.com/MythreyaK updated https://github.com/llvm/llvm-project/pull/152445

>From 1b2cb7c27b72d1a774aa7ac0652f3765defa1140 Mon Sep 17 00:00:00 2001
From: Mythreya Kuricheti <git at mythreya.dev>
Date: Wed, 6 Aug 2025 22:49:28 -0700
Subject: [PATCH] [clang] CodeComplete fix for addr of deduced-this methods

---
 .../clangd/unittests/CodeCompleteTests.cpp    | 11 ++++----
 clang/lib/Sema/SemaCodeComplete.cpp           | 25 +++++++++++++------
 .../skip-explicit-object-parameter.cpp        |  4 +--
 3 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp b/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp
index 61bd6318b46cf..8a7188ee7260c 100644
--- a/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp
+++ b/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp
@@ -4462,15 +4462,16 @@ TEST(CompletionTest, SkipExplicitObjectParameter) {
                                Preamble.get(), Inputs, Opts);
     EXPECT_THAT(
         Result.Completions,
-        ElementsAre(AllOf(named("foo"), signature("<class self:auto>(int arg)"),
-                          snippetSuffix("<${1:class self:auto}>"))));
+        ElementsAre(AllOf(named("foo"), signature("(auto &&self, int arg)"),
+                          snippetSuffix("(${1:auto &&self}, ${2:int arg})"))));
   }
   {
     auto Result = codeComplete(testPath(TU.Filename), Code.point("c3"),
                                Preamble.get(), Inputs, Opts);
-    EXPECT_THAT(Result.Completions,
-                ElementsAre(AllOf(named("bar"), signature("(int arg)"),
-                                  snippetSuffix(""))));
+    EXPECT_THAT(
+        Result.Completions,
+        ElementsAre(AllOf(named("bar"), signature("(A self, int arg)"),
+                          snippetSuffix("(${1:A self}, ${2:int arg})"))));
   }
 }
 } // namespace
diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
index 0de55800ccdd1..357798e20aca3 100644
--- a/clang/lib/Sema/SemaCodeComplete.cpp
+++ b/clang/lib/Sema/SemaCodeComplete.cpp
@@ -1312,6 +1312,11 @@ bool ResultBuilder::canCxxMethodBeCalled(const CXXMethodDecl *Method,
       (CurrentClassScope == Method->getParent() ||
        CurrentClassScope->isDerivedFrom(Method->getParent()));
 
+  // if method is using C++23 "deducing this", then it is a call
+  if (Method->isExplicitObjectMemberFunction()) {
+    FunctionCanBeCall = true;
+  }
+
   // We skip the following calculation for exceptions if it's already true.
   if (FunctionCanBeCall)
     return true;
@@ -3240,6 +3245,7 @@ static std::string GetDefaultValueString(const ParmVarDecl *Param,
 static void AddFunctionParameterChunks(Preprocessor &PP,
                                        const PrintingPolicy &Policy,
                                        const FunctionDecl *Function,
+                                       const CodeCompletionContext &CCContext,
                                        CodeCompletionBuilder &Result,
                                        unsigned Start = 0,
                                        bool InOptional = false) {
@@ -3255,15 +3261,17 @@ static void AddFunctionParameterChunks(Preprocessor &PP,
                                 Result.getCodeCompletionTUInfo());
       if (!FirstParameter)
         Opt.AddChunk(CodeCompletionString::CK_Comma);
-      AddFunctionParameterChunks(PP, Policy, Function, Opt, P, true);
+      AddFunctionParameterChunks(PP, Policy, Function, CCContext, Opt, P, true);
       Result.AddOptionalChunk(Opt.TakeString());
       break;
     }
 
     // C++23 introduces an explicit object parameter, a.k.a. "deducing this"
     // Skip it for autocomplete and treat the next parameter as the first
-    // parameter
-    if (FirstParameter && Param->isExplicitObjectParameter()) {
+    // parameter. But if the context is a symbol, i.e., "A::method" call,
+    // do not skip
+    auto IsSymbol = CCContext.getKind() == CodeCompletionContext::CCC_Symbol;
+    if (FirstParameter && Param->isExplicitObjectParameter() && !IsSymbol) {
       continue;
     }
 
@@ -3726,7 +3734,7 @@ CodeCompletionString *CodeCompletionResult::createCodeCompletionStringForDecl(
                                    Ctx, Policy);
     AddTypedNameChunk(Ctx, Policy, ND, Result);
     Result.AddChunk(CodeCompletionString::CK_LeftParen);
-    AddFunctionParameterChunks(PP, Policy, Function, Result);
+    AddFunctionParameterChunks(PP, Policy, Function, CCContext, Result);
     Result.AddChunk(CodeCompletionString::CK_RightParen);
     AddFunctionTypeQualsToCompletionString(Result, Function);
   };
@@ -3808,7 +3816,7 @@ CodeCompletionString *CodeCompletionResult::createCodeCompletionStringForDecl(
 
     // Add the function parameters
     Result.AddChunk(CodeCompletionString::CK_LeftParen);
-    AddFunctionParameterChunks(PP, Policy, Function, Result);
+    AddFunctionParameterChunks(PP, Policy, Function, CCContext, Result);
     Result.AddChunk(CodeCompletionString::CK_RightParen);
     AddFunctionTypeQualsToCompletionString(Result, Function);
     return Result.TakeString();
@@ -7132,13 +7140,16 @@ void SemaCodeCompletion::CodeCompleteConstructorInitializer(
   auto GenerateCCS = [&](const NamedDecl *ND, const char *Name) {
     CodeCompletionBuilder Builder(Results.getAllocator(),
                                   Results.getCodeCompletionTUInfo());
+    auto CCContext = Results.getCompletionContext();
     Builder.AddTypedTextChunk(Name);
     Builder.AddChunk(CodeCompletionString::CK_LeftParen);
     if (const auto *Function = dyn_cast<FunctionDecl>(ND))
-      AddFunctionParameterChunks(SemaRef.PP, Policy, Function, Builder);
+      AddFunctionParameterChunks(SemaRef.PP, Policy, Function, CCContext,
+                                 Builder);
     else if (const auto *FunTemplDecl = dyn_cast<FunctionTemplateDecl>(ND))
       AddFunctionParameterChunks(SemaRef.PP, Policy,
-                                 FunTemplDecl->getTemplatedDecl(), Builder);
+                                 FunTemplDecl->getTemplatedDecl(), CCContext,
+                                 Builder);
     Builder.AddChunk(CodeCompletionString::CK_RightParen);
     return Builder.TakeString();
   };
diff --git a/clang/test/CodeCompletion/skip-explicit-object-parameter.cpp b/clang/test/CodeCompletion/skip-explicit-object-parameter.cpp
index 587d6cb044d19..f88f1543e0081 100644
--- a/clang/test/CodeCompletion/skip-explicit-object-parameter.cpp
+++ b/clang/test/CodeCompletion/skip-explicit-object-parameter.cpp
@@ -36,9 +36,9 @@ int func3() {
   (&A::bar)
 }
 // RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:%(line-3):10 -std=c++23 %s | FileCheck -check-prefix=CHECK-CC3 %s
-// CHECK-CC3: COMPLETION: foo : [#void#]foo<<#class self:auto#>>(<#int arg#>)
+// CHECK-CC3: COMPLETION: foo : [#void#]foo(<#auto &&self#>, <#int arg#>)
 // RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:%(line-4):10 -std=c++23 %s | FileCheck -check-prefix=CHECK-CC4 %s
-// CHECK-CC4: COMPLETION: bar : [#void#]bar(<#int arg#>)
+// CHECK-CC4: COMPLETION: bar : [#void#]bar(<#A self#>, <#int arg#>)
 
 int func4() {
   // TODO (&A::foo)(